Steps to Configure and Verify Interswitch Connectivity

VLAN stands for Virtual Local Area Network. It is a 12-bit identity used to create multiple broadcast domains in a switch. VLAN ranges from 0 to 4095 (VLAN 0 and VLAN 4095 are reserved and not used).

Modes of Switch port: 

Administrative mode: 

• This Switch Port mode is configured by the admin.
• Types of Administrative mode: 
  • Static Access – (no negotiation of the trunk)
  • Static Trunk – (forces formation of the trunk)
  • Dynamic Desirable – (initiates negotiation of the trunk)
  • Dynamic Auto – (wait for the negotiation of the trunk)

Operational Mode: 

• This is the resulting mode of the Switch Port after the negotiation (the result of the configuration done by the admin).
• Types of Operational mode:

Access Mode – If the port is in access mode then the port can carry only one VLAN data. It is only configured on the ports connected to the end users.

switch(config)#int <interface_id>
switch(config-if)#Switch Port mode access

Trunk Mode -If the port is in Trunk mode then the port can carry multiple VLAN data using the Layer 2 encapsulation protocol (either Dot1Q or ISL).

switch(config)#int <interface_id>
switch(config-if)#Switch Port mode trunk

Configuring and Verifying Inter-switch Connectivity:

Configure IP Address On the Virtual PCs:

PC1:

PC2:

PC3:

PC4:

Configure VLANs On both Switches:

Switch(config)#VLAN 10
Switch(config-VLAN)#exit
Switch(config)#VLAN 20
Switch(config-VLAN)#exit

Switch1: 

Switch2: 

Add the Switch Ports Connected to End-Users:

Switch(config)#int <interface_id>
Switch(config-if)#Switch Port mode access
Switch(config-if)#Switch Port access VLAN <VLAN_number>
Switch(config-if)#exit

Switch1: 

Switch2: 

Let’s check the connectivity between PCs Right now.

As you can see, none of the PCs can communicate to each other. 

• PC1 and PC2 are not able to communicate because of different VLANs.
• PC1 and PC3 are not able to communicate because there is no Inter-switch connectivity.
• PC1 and PC4 are not able to communicate because of different VLANs and no Inter-switch connectivity.

Configure Trunk Ports on Switch:

Switch(config)#int <interface_id>
Switch(config-if)#Switch Port trunk encapsulation <dot1q/isl>
Switch(config-if)#Switch Port mode trunk
Switch(config-if)#exit

Switch1: 

Switch2: 

Verifying Connectivity:

PC1 to PC3: 

PC2 to PC4: 

As you can see, Inter-switch connectivity has been established and the connection is successful in devices within the same VLANs.